The purpose of this project is to study the genome structure and gene functions of avian and mammalian RNA tumor viruses. The specific areas of research for the coming year include: (a) to study the genome structure of avian reticuloendotheliosis virus and other acute leukemia viruses by oligonucleotide finger-printing and heteroduplex mapping; (b) to characterize the transformation-specific sequences of acute leukemia viruses by isolating specific complimentary DNA; and (c) to study the functions of in vitro synthesized DNA by in vitro transcription.